Contact tubes are known which are punched out of a metal sheet, the cylindrical tube body being produced by rolling and/or bending the punched metal sheet, and an elastic behaviour being achieved by leaving a gap parallel to the plug-in axis between the facing punched edges, and keeping the inside diameter of the cylindrical tube slightly smaller with respect to the diameter of the plug part to be plugged in, whilst producing holding forces upon plugging in because of the required widening of the cylindrical lateral surface. This type of plug sleeve does not permit an effectively reproducible contact resistance to be produced, since the surface where the plug parts are seated on one another can vary very considerably from one plug to another.
An improvement is achieved in the case of a cylindrical tube by punching out of the cylindrical lateral surface spring tongues which are bent into the tube interior in order thereby to produce defined contact surfaces. This is already a great improvement with regard to the reproducibility of the contact situation. With regard to the elasticity of these contact springs, and to the contact pressure, such contact tubes are still not ideal, however, since although long contact springs permit excellent elastic properties and large spring excursions, they permit only a slight contact pressure. Short contact springs make it difficult to insert the mating connector, but deliver an acceptable contact pressure.
It is the object of the present invention to improve a cylindrical contact tube so as to ensure a large contact pressure between the contact surfaces in conjunction with good elastic properties which simplify the insertion of the mating connector.
This object is achieved in accordance with the claim. The subclaims characterize preferred embodiments of the invention.